Top U.S. weather story of 2009: drought hits a 10-year low

The weather gods were unusually kind to the U.S. in 2009, as the nation had no hurricane landfalls, a relatively quiet tornado season, no billion-dollar floods, and the lowest drought footprint of the decade by year's end. According to insurance giant Munich Re, the four costliest 2009 weather disasters in the U.S., not including droughts, were:

Costliest U.S. weather disaster of 2009: the Texas droughtThe costliest U.S. weather disaster in 2009 was the Texas drought. According to preliminary estimates, the agricultural losses from the Texas drought will cost close to $4 billion. The drought actually began in 2007 - 2008, and at the beginning of 2009 (Figure 2), much of Texas was already experiencing "exceptional drought"--the highest level of drought classified by the U.S. Drought Monitor. By summer, much below-average rainfall and scorching triple-digit heat caused the exceptional drought region to expand over a large region of South Central Texas. However, by September, the southern branch of the jet stream became more active, as it typically does during strong El Niño events in the Eastern Pacific, putting southern Texas in the path of a series of drought-busting rain storms that continued into the winter. By December, just a few spots of moderate to severe drought remained in Texas. While the short-term drought is over, longer-term drought remains in Texas. Area lakes have seen only modest rises, and will take months to show significant improvements. Lake Corpus Christi was just 33% of capacity on December 26, and other South Central Texas lakes and reservoirs were between 59% and 100% of capacity. With El Niño conditions expected to continue through winter and spring, there is a good chance that Texas will enter summer 2010 free of both short and long-term drought, though.

Figure 2. What a difference a year makes: Texas began the year with exceptional drought conditions over a small region, which expanded to cover a large portion of the state in the summer. Fall and winter rains broke the drought, and by December only a few small spots of drought remained over Texas. The Southeast U.S. also began the year with widespread drought conditions, which eased by summer. However, drought conditions developed over the Desert Southwest, including most of Arizona. Image credit: U.S. Drought Monitor.

Top U.S. weather story of 2009: drought at a 10-year lowAs of December 2009, the U.S. was free of "exceptional drought" for the first time since June 2008, and had the lowest levels of the two highest drought categories--"extreme" and "exceptional"--since June 2005. According to the U.S. Drought Monitor archive, the 4.24% of the country experiencing severe or higher drought conditions in December 2009 was the lowest U.S. drought footprint of the decade (Figure 3). The previous low was 4.57%, in November 2005. This is very good news, since droughts typically cost the U.S. an average of $6 - $8 billion per year, and are our costliest weather-related disasters, according to FEMA. For comparison, Floods cause an average damage of $2.4 billion per year, and hurricanes, $1 - $5 billion per year.

Figure 3. Areal coverage of drought over the Contiguous U.S. from January 2000 to December 2009. Dark red colors are the highest level of drought, "exceptional"; bright red colors include the the next highest level of drought, "extreme (D3); orange colors include the next highest level of drought, "severe" (D2); light orange colors include next highest level of drought conditions, "moderate" (D1); and yellow colors include the lowest level of drought conditions, "Abnormally Dry" (D0). At the end of 2009, the Contiguous U.S. was experiencing its lowest drought footprint of the decade. Image credit: U.S. Drought Portal, National Integrated Drought Information System.

Drought is not increasing in the U.S.Global warming theory predicts that although global precipitation should increase in a warmer climate, droughts will also increase in intensity, areal coverage, and frequency (Dai et al., 2004). This occurs because when the normal variability of weather patterns brings a period of dry weather to a region, the increased temperatures due to global warming will intensify drought conditions by causing more evaporation and drying up of vegetation. Increased drought is my number one concern regarding climate change for both the U.S. and the world over the next forty years. Two of the three costliest U.S. weather disasters since 1980 have been droughts--the droughts of 1988 and 1980, which cost $71 billion and $55 billion, respectively. The heat waves associated with these droughts claimed over 17,000 lives, according to the National Climatic Data Center publication, Billion-Dollar Weather Disasters. Furthermore, the drought of the 1930s Dust Bowl, which left over 500,000 people homeless and devastated large areas of the Midwest, is regarded to be the third costliest U.S. weather disaster on record, behind Katrina and the 1988 drought. (Ricky Rood has an excellent book on the Dust Bowl that he recommends in his blog post from January). However, despite significantly warmer temperatures over the U.S. over the past 40 years, drought has not increased, according to the U.S. Climate Extremes Index (blue bars, Figure 4). The portion of the U.S. experiencing abnormal drought and exceptionally wet conditions has remained nearly constant at 10% over the past century. A recent paper by Andreadis et al., 2006, summed up 20th century drought in the U.S.: "Droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the country over the last century. The main exception is the Southwest and parts of the interior of the West, where, notwithstanding increased precipitation (and in some cases increased soil moisture and runoff), increased temperature has led to trends in drought characteristics that are mostly opposite to those for the rest of the country especially in the case of drought duration and severity, which have increased."

Figure 4. The Climate Extremes Index for January through November for drought (the December stats are not yet available, but the Jan - Nov numbers will not be much different). The worst U.S. droughts on record occurred in the 1930s and 1950s. There has been no trend in the amount of the U.S. covered by drought conditions (blue bars) or by abnormally moist conditions (red bars) over the past century. About 10% of the U.S. is typically covered by abnormally dry or wet conditions (black lines). Image credit: National Climatic Data Center.

Next postHave a great rest of the decade, everyone, and I'll be back next decade with a new post on the top global weather story of 2009 (yes, I realize that the end of the decade is really on December 31, 2010, but I'll go with the flow on this! I want to thank all of you who helped out the Portlight charity cause this year, everyone who uploaded a wunderphoto, and everyone who participated in the great community we've built here at Wunderground! I look forward to 2010.

Most of Texas has been under serious drought conditions for about a year and a half. Much of the state is under Extreme Drought conditions. The agricultural/ranching/rural areas of the county are most affected, as the drought has a direct and significant impact on the livelihood of those making their living in a way dependent on nature. The importance of rain to daily life is reflected in this sign at a church in rural George West, Texas, in Live Oak, County.

Quoting AstroHurricane001:Hmm, all this talk of snow in Florida makes me think that Arctic air is flooding into the Northern continents (unpredicted cold weather and snow seen in North America, Europe and Asia) and leaving the oceans warm. Accuweather is predicting...uh...crazy snowfall amounts. The global ocean currents even seem like they're slowing down. By the way, I have some links to 48-hour satellite loops from December on my blog. I didn't post them here because that would stretch the blog (and they didn't work). Anyway, hope everyone is having a great New Year. Be resillient to the weather.

Astro, unprecidented, no, unusual for the Deep South/S Plains, yes! Maybe the coldest air is several years. IF the upper level pattern dumped all the Siberian air in at once, then you'd see widespread records falling. The GFS, GFSX, EMCWF send the Arctic air down in a few waves, not all at once! Thankfully. Our El Nino is acting like a "La Nina", with a moist, wild, kick, kinda' like an URGE!!

Quoting Bordonaro:Drak, those Thursday 1-7-10 temps look about right. They could be coider IF the trough digs deeper into the Southern US. One GFS computer model showed a long wave trough from Maine to New Mexico. IF that happens, its going to be real ugly, say 5F colder across the South! Oh boy, 28F for Dallas Ft Worth, TX :0)

That would mean mid 50s for SFL for highs.. and low 30s for lows? Sike..

Drak, those Thursday 1-7-10 temps look about right. They could be coider IF the trough digs deeper into the Southern US. One GFS computer model showed a long wave trough from Maine to New Mexico. IF that happens, its going to be real ugly, say 5F colder across the South! Oh boy, 28F for Dallas Ft Worth, TX :0)

Hmm, all this talk of snow in Florida makes me think that Arctic air is flooding into the Northern continents (unpredicted cold weather and snow seen in North America, Europe and Asia) and leaving the oceans warm. Accuweather is predicting...uh...crazy snowfall amounts. The global ocean currents even seem like they're slowing down. By the way, I have some links to 48-hour satellite loops from December on my blog. I didn't post them here because that would stretch the blog (and they didn't work). Anyway, hope everyone is having a great New Year. Be resillient to the weather.

I've been in and out of the blog, but just reading, not posting. Just ended my holiday travel, having made trips to Boston, MA and South Florida. I was fortunate enough to miss the snowstorms prior to Christmas, and at the same time I enjoyed the cooler temps which we have not been experiencing here in Nassau. Today it's sunny and mild, but temps are forecast to get to mid 80s before a quasi-cold front passes through. So far it's looking like the only chance I will have to wear my winter gear has already passed.... lol

(no, not really, they went under I think. I once lived only a couple of miles from the Supreme refinery near Labadieville. The air was sweet when the wind blew the right way. Now I get paper mill stink with a NNE wind. Bad trade!)

And, AIM, I was not doing the Hebrew thing. I was wondering when we would get all post right to left.

I've been tracking the shipment, still don't know why it hasn't arrived. I hope it doesn't freeze before it gets there. Could you imagine a case of sodas exploding! I put a can of Ginger Ale in the freezer once to cool it fast and forgot about it. Not a pretty sight!!!!!

.DISCUSSION...CLOUDS WILL BE CLEARING FROM NW TO SE ACROSS THE AREA FOR THE NEXTSEVERAL HOURS. SUSPECT THEY WILL PUSH ALL THE WAY OFF THE COASTBY MID MORNING AND SE TX WILL GET ANOTHER SHORT GLIMPSE OF THE SUNTODAY AND SATURDAY. HIGH PRES MOVES EAST ON SUN AND COASTAL TROFBEGINS TO DEVELOP. ISENTROPIC LIFT WILL BRING INCREASED CLOUDINESSTO THE REGION SAT NIGHT AND SUN. COULD SEE SOME SCT SHRA ON SUNESP CLOSER TO THE COAST AND OFFSHORE. ANOTHER COLD FRONT PUSHESTHRU THE REGION SUNDAY NIGHT FOLLOWED BY A FEW MORE COOL DRY DAYSWITH HIGH PRES DOMINATING.

ONSHORE FLOW RESUMES LATE TUES AS HIGH PRES MOVES OFF TO THE EAST.WESTERN H5 RIDGE AMPLIFIES ALLOWING COLD ARCTIC AIRMASS TO PLUNGE SWDINTO SE TX LATE WED OR EARLY THURS (ASSUMING THE CURRENT FCSTTRAJECTORY HOLDS). WILL PROBABLY SEE SOME PRECIP AHEAD OF THE FRONT ONWED...HOPEFULLY PUSHING E/SE BEFORE THE MUCH COLDER TEMPS ARRIVE.

MODELS HAVE BEEN HINTING AT THIS FOR SOME TIME NOW AND WILLCONTINUE TO TWEAK FCST TEMPS DOWN ASSUMING CONTINUED MODELCONSISTENCY. STUCK WITH 20S FOR LOWS AND 30S FOR HIGHS NEXTTHUR/FRI BUT RAW DATA SUPPORTS EVEN COLDER READINGS.

Quoting AwakeInMaryland:730. Nah, Grothar, you know enough languages! I tasked Atmo with that one (he started it, saying maybe the WU "improved"(?) site might need to have a left-to-right default...Atmo declined, as he was only on his second cup of coffee!

I NEED AN "URGE" UPDATE...T-Dude is igg'ing me...that won't work!!

I've been tracking the shipment, still don't know why it hasn't arrived. I hope it doesn't freeze before it gets there. Could you imagine a case of sodas exploding! I put a can of Ginger Ale in the freezer once to cool it fast and forgot about it. Not a pretty sight!!!!!

Quoting tornadodude:I have been to West Virginia once, had an amazing trip. went camping, rock climbing, and white water rafting (: I went to Fayetteville and went to New River Gorge, it was great!

New River Gorge is waycool. I'd like to go up there for "Bridge Day". They close it and let folks bungee jump and base jump from it. I'd like to bungee jump from it. I've done it a couple of times in PC Beach back in the nineties. It was from a crane tho. Id like to do it from the New River Gorge Bridge. What a rush!!

With the models trends, I wouldn't be surprised to see freezing conditions into South Florida and a hard freeze for central and northern Florida. The GFS is trending colder as well as the GGEM who indicates temps in the 20s infiltrating into South Florida.

730. Nah, Grothar, you know enough languages! I tasked Atmo with that one (he started it, saying maybe the WU "improved"(?) site might need to have a left-to-right default...Atmo declined, as he was only on his second cup of coffee!

As i stated last night -2 at 850 that far south is tough to verify, but it's not impossible. We'll probably have some more wind chill advisories over the next week or two. The criteria for that in east central Florida is only 35 with 10 mph winds or greater.We might even see some advection freezes across central Florida, which means freezing temperatures with the wind still blowing, as opposed to radiational cooling freezes where there's a big high centered over us and we drop to 32 due to raditional cooling. Looks like some prefrontal shower activity for us later this afternoon with the cold airmass to follow. Regardless should be an interesting period ahead temperature wise!

adrian

With the models trends, I wouldn't be surprised to see freezing conditions into South Florida and a hard freeze for central and northern Florida. The GFS is trending colder as well as the GGEM who indicates temps in the 20s infiltrating into South Florida.

Happy New Year Everyone! Hey Awake, you want me to try learning Hebrew. Tried it a little, but without the vowels on top, it was too difficult. Hope everyone is recovering from last night! It was a perfect night here is Ft. Lauderdale. The moon was so bright, we didn't have to turn on the lights. They still haven't told us how cold it will be here yet. Probably still don't know.

Quoting Drakoen:Whatever happens it looks like things will get dramatically colder for an extended period of time.

As i stated last night -2 at 850 that far south is tough to verify, but it's not impossible. We'll probably have some more wind chill advisories over the next week or two. The criteria for that in east central Florida is only 35 with 10 mph winds or greater.We might even see some advection freezes across central Florida, which means freezing temperatures with the wind still blowing, as opposed to radiational cooling freezes where there's a big high centered over us and we drop to 32 due to raditional cooling. Looks like some prefrontal shower activity for us later this afternoon with the cold airmass to follow. Regardless should be an interesting period ahead temperature wise!